| 摘要 |
An adapter device includes a DC/DC adapter to receive DC power from a DC power source, and output a regulated DC voltage (V<SUB>out</SUB>). A source determination circuitry receives the DC power from the DC power source and compares a magnitude of a voltage of the DC power with a reference magnitude of a reference voltage (V<SUB>ref</SUB>). When the magnitude of the voltage of the DC power is greater than the reference magnitude, a data signal (V<SUB>data</SUB>) having a first value is output. When the magnitude of the voltage of the DC power is less than the reference magnitude, the V<SUB>data </SUB>signal having a second value is output. The V<SUB>data </SUB>signal is received by control circuitry of an electronic device. When the V<SUB>data </SUB>signal has the first value, the electronic device operates in a first mode where battery charging circuitry is disabled. When the V<SUB>data </SUB>signal has the second value, the battery charging circuitry is enabled.
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